The visual effect of a lacquered or multi-layer coated surface results from the interplay of various optical impressions, such as gloss and structure, and such as colour shade, which in turn is composed of colour location, brightness and colour intensity, for example. In the case of multi-layer coatings, the visual impression generally originates not only from the outer lacquer coat, but may also be influenced by one or more lacquer coats situated underneath. There is a wealth of methods which are known for the characterisation of a lacquered surface and which are suitable for describing the visual effect thereof on the eye of an observer. Examples include methods, which are known to one skilled in the art and which operate based on optical principles, of gloss measurement, of measuring gloss fogging (haze), of measuring colour shade (colorimetry) and of determining surface structures. One important influencing variable as regards the visual effect of a lacquered surface is the coat thickness at which the respective lacquer coat or respective lacquer coats have been applied. If a surface which is provided with a single-layer coating or a multi-layer coating is to be characterised as regards its visual effect as a function of the coat thickness of a specific lacquer coat or of the coat thickness of lacquer coats of particular interest, it is necessary to lacquer and measure a multiplicity of test panels. This multiplicity results firstly from the necessity of having to lacquer a plurality of test panels at different coat thicknesses, and secondly in order to obtain a statistical mean, which first ensures reproducibility of the readings obtained. The meaningfulness of readings obtained in this manner must nevertheless be considered critically, since a correlation with the visual impression is only obtained to a limited extent.